The present invention relates to a system for treating vascular disease. More specifically, the present invention relates to a system for performing dilatation and for deploying a stent in a bifurcation lesion.
Vascular disease currently represents a prevalent medical condition. Typical vascular disease involves the development of a stenosis in the vasculature. The particular vessel containing the stenosis can be completely blocked (or occluded) or it can simply be narrowed (or restricted). In either case, restriction of the vessel caused by the stenotic lesion results in many well known problems caused by the reduction or cessation of blood circulation through the restricted vessel.
A bifurcation is an area of the vasculature where a first (or parent) vessel is bifurcated into two or more branch vessels. It is not uncommon for stenotic lesions to form in such bifurcations. The stenotic lesions can affect only one of the vessels (i.e., either of the branch vessels or the parent vessel) two of the vessels, or all three vessels.
Vascular stents are also currently well known. Vascular stents typically involve a tubular stent which is movable from a collapsed, low profile, delivery position to an expanded, deployed position. The stent is typically delivered using a stent delivery device, such as a stent delivery catheter. In one common technique, the stent is crimped down to its delivery position over an expandable element, such as a stent deployment balloon. The stent is then advanced using the catheter attached to the stent deployment balloon to the lesion site under any suitable, commonly known visualization technique. The balloon is then expanded to drive the stent from its delivery position to its deployed position in which the outer periphery of the stent frictionally engages the inner periphery of the lumen. In some instances, the lumen is predilated using a conventional dilatation catheter, and then the stent is deployed to maintain the vessel in an unoccluded, and unrestricted position.
While there have recently been considerable advances in stent design and stent deployment techniques, there is currently no adequate method of treating bifurcation lesions, particularly where both downstream branch vessels are affected by the lesion. Current techniques of dealing with such lesions typically require the deployment of a slotted tube stent across the bifurcation. However, this compromises the ostium of the unstented branch.
Further, once the first stent is deployed, the treating physician must then advance a dilatation balloon between the struts of the stent already deployed in order to dilate the second branch vessel. The physician may then attempt to maneuver a second stent through the struts of the stent already deployed, into the second branch vessel for deployment. This presents significant difficulties. For example, dilating between the struts of the stent already deployed tends to distort that stent. Further, deploying the second stent through the struts of the first stent is not only difficult, but it can also distort the first stent.
In addition, the current systems used to deploy stents in a bifurcated lesion have other significant disadvantages. For example, such techniques typically involve the advancement of a guidewire past the bifurcation lesion, and into a first of the branch vessels. That guidewire is then used to advance the predilitation device to dilate the vessel, and then to advance the stent deployment device to deploy the stent in the parent vessel and in the first branch vessel. Then, the guidewire must be withdrawn from the first branch vessel and then maneuvered and advanced through the structure of the first stent and into the second branch vessel. The guidewire is then used for guiding advancement of the dilatation device into the second branch vessel, and for guiding advancement of the stent deployment device into the second branch vessel for deployment of the second stent.
Also, there are currently no stents having shapes which closely conform to the geometry of a typical bifurcation. Thus, the deployment of a conventional stent in a bifurcation lesion either leaves one of the branch stents impinging on the ostium of the other branch, or leaves a significant portion of the vessel wall in the area of the bifurcation unstented.